Recording method using recording liquid having organic solvent with plural (C2 H4 O) moieties

ABSTRACT

A recording method using a recording liquid composition having at least water, a water-soluble dye and an organic solvent represented by formulae (I), (II), or (III): 
     
         R.sub.1 O--(C.sub.2 H.sub.4 O).sub.m --R.sub.2             (I) 
    
     
         HO--(C.sub.2 H.sub.4 O).sub.a (C.sub.3 H.sub.6 O).sub.b (C.sub.2 H.sub.4 
    
      O) c  H                                                (II) 
     
         (R.sub.3) (R.sub.4)PH--O--(C.sub.2 H.sub.4 O).sub.n H      (III).

This application is a division of allowed application Ser. No. 168,593filed Mar. 3, 1988, U.S. Pat. No. 4,923,515, which is a continuation ofabandoned application Ser. No. 891,596 filed Aug. 1, 1986, nowabandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a recording liquid to be used for variousrecording tools such as writing implements, printers, etc. (hereinaftercalled an ink), particularly an ink suitable for the ink jet recordingsystem in which recording is performed by permitting liquid droplets tofly from an orifice of recording head and also to a recording method byuse thereof.

2. Description of the Related Art

The ink jet recording system has the advantages of less noise generationduring recording as well as easy adaptation to color recording andcapability of giving recorded images of high resolution at high speed.In the ink jet recording system, solutions of various water-soluble dyesdissolved in water or mixtures of water with organic solvents have beenused as the ink. In this case, the requisite characteristics of the inkto be used are physical values of viscosity, surface tension, etc.,within appropriate ranges, high dissolving stability of the dissolvedcomponents, no clogging of minute orifices, capability of givingrecorded images with sufficiently high density, no change in physicalvalues or no precipitation of solid components during storage, etc.Further, in addition to the above characteristics, it is also requiredto have the properties such that recording may be performed withoutrestriction with respect to the kind of recording medium, that thefixing speed may be great, that the recorded images may be excellent inlight resistance, water resistance, and solvent resistance (particularlyalcohol resistance), and also that recorded image with excellentresolution may be given.

In the prior art, as the colorant of the ink in the ink jet recordingsystem, water-soluble dyes have been primarily employed o0 account ofthe liquid medium being aqueous and, by use of water-soluble dyes, manyof the above basic requirements for the ink jet recording system havebeen satisfied. However, when water-soluble dyes are used, since thesewater-solubles are inherently inferior in light resistance, problems arefrequently involved in light resistance of the recorded images. Morespecifically, when recorded images are exposed to the light from thelight sources such as sun light, fluorescent lamp or projector, therecorded images may be extinguished, or become less readable, or theimage may be faded during a prolonged term of storage. Accordingly,investigations have been made regarding the addition of variousadditives such as UV-absorbers or antioxidants for improvement of lightresistance with the basic characteristics maintained as mentioned abovefor the ink for ink jet recording. Thereby, it has been expected toimprove greatly light resistance of the recorded images by addition ofsuch substances into an ink.

However, this kind of additive is inferior in solution stability in theliquid medium of ink particularly in solution stability in water, thusensuing the problems that it precipitates as solid in the ink with lapseof time, or that it precipitates the dye by decomposing or isomerizingthe dye, thereby causing generation of clogging of nozzles.

The ink jet recording method, although it has been said not to beparticular as to paper and more easily adapted to plain paper ascompared with other recording methods, is not yet satisfactory under thepresent condition. More specifically, when printing is effected on plainpaper commonly used in offices other than the paper for ink jetrecording, such as notebooks, reporting paper, copying paper, letterpaper, etc., the printed ink will spread along the fibers of the paper,whereby dot shape becomes unstable to generate so called feathering andtherefore fine ruled lines, fine letters or complicated chinesecharacters become frequently unclear and difficult to see.

Further, since the papers as mentioned above are subjected to thetreatment called "sizing" so that feathering ma be retarded in letterswritten by a writing implement with the use of an aqueous ink forfountain pen, the ink cannot easily penetrate into the paper in theprinting conducted when by an ink jet printer, resulting in poor dryingcharacteristic at the printed portion, whereby there are involved theproblems such that the printed letters are stained by smearing with thecover of the printer and that the ink is transferred to the hand whenthe printed matter is touched with a hand.

Accordingly, various improvements have been done for the purpose ofimproving feathering and drying characteristic of printed letters. Forexample, it has been attempted to make the pH of the ink alkaline or toadd a large amount of a surfactant in the ink, etc. An ink having a pHof strongly alkaline is dangerous when the ink is touched with hands andalso involves the drawbacks that it is not sometimes good in bothfeathering and drying characteristic for papers in which a certain kindsof sizing agents are employed. On the other hand, addition of a largeamount of a surfactant causes such problems that feathering occurredremarkably depending on the paper, that the ink was not ejected butretracted from the orifice face depending on the conditions of the printhead or contrariwise the whole orifice face was wetted to give noejection of ink, etc.

Although various improvements other than those as described above havebeen hitherto attempted, under the present condition, no ink has beenknown which can solve all of the problems of aforesaid feathering anddrying characteristic of printed letters.

SUMMARY OF THE INVENTION

Accordingly, a principal object of the present invention is to providean ink improved in the above drawbacks and a recording method by usethereof, namely an ink excellent in solution stability of awater-soluble dye as the ink for various writing implements, printers,particularly for ink jet recording and also capable of giving imageshaving excellent light resistance and a recording method by use thereof.Further, another object of the present invention is to provide an inkwhich can give an image of good printing quality and also has gooddrying characteristic, without feathering or deformation of letters whenprinted on ordinary plain paper, etc. used in offices and a recordingrecording method by use thereof.

According to an aspect of the present invention, there is provided arecording liquid, comprising at least water, an organic solvent and awater-soluble dye, said water-soluble dye having a solubility of 5 % byweight or less in said organic solvent.

According to another aspect of the present invention, there is provideda recording method which performs recording by attaching liquid dropletsof a recording liquid onto a recording medium, said recording liquidcomprising at least water, an organic solvent and a water-soluble dye,said water-soluble dye having a solubility of 5 % by weight or less insaid organic solvent, said recording medium being subjected to sizingand having fibers exposed on the surface of the recording medium.

The above objects can be accomplished by the present invention asdefined below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To describe in more detail about the present invention, it has beenpracticed in the art to add a high boiling and water-soluble organicsolvent such as polyhydric alcohols, etc., to an ink containing awater-soluble dye, particularly an ink for ink jet recording, in orderto prevent ejecting nozzles, etc. from clogging by drying. Whenrecording is effected on highly sized paper and the like, due to lowliquid absorption of the paper, less volatile organic solvent willremain on the paper even if the water in the ink may be rapidlyevaporated, and so the dye remains in a dissolved state. Accordingly,there ensue the problems such that the head or fingers may be stainedwhen touched with the printed paper and also that the printed lettersmay be disturbed.

On the other hand, in the case of a paper with low degree of sizinghaving fibers exposed on the surface such as the papers for office work,the organic solvent will similarly remain even if the water may beevaporated and also, since the dye is dissolved in the organic solvent,the dye solution will be spread along the fibers of the paper or intothe voids between the fibers, whereby, etc., impairing the quality ofprinted letter.

Therefore, such an ink for ink jet recording may ideally contain a dyein dissolved state when residing within the instrument such as nozzles,etc., of the recording device, but will not easily give rise tofeathering by precipitation of the dye in the ink from the ink medium,and various problems as mentioned above were expected to be solved byuse of such an ink.

The present inventors have intensively studied in order to obtain suchan ideal ink, and consequently found that by selecting and using anorganic solvent which can dissolve sufficiently a dye in a mixture ofwater with an organic solvent and afford rapid precipitation of the dyewhen the ratio of water is lowered by evaporation of the water in themixture on a recording medium, there occurs no staining of other partscontacted with the printed portion or disturbance of printed letterseven when printed on a paper with high degree of sizing, because the dyein the ink can be rapidly precipitated by evaporation of the water inthe ink, and also printing of high quality is possible on the paper withlow degree of sizing as the result of rapid precipitation of the dye bysimilar evaporation of the solvent, whereby only the liquid medium isfeathered into the paper without feathering of the dye.

Studies have been made about organic solvents which can give suchpreferable results as mentioned above, and it has been consequentlyfound that the above preferable effect, namely the effect that the dyeis maintained sufficiently under dissolved state before evaporation ofthe water (within recording instrument or nozzle) and the dye is readilyprecipitated by evaporation of water (on paper), can be exhibited whenthe solubility of a water-soluble dye in such an organic solvent is 5 %by weight or less, and more preferably 4.5 % by weight or less.

The water-soluble dye in the ink to be used in the present inventionwhich first characterizes the present invention may be those which areknown per se, including, for example, water-soluble dyes as representedby direct dyes, acidic dyes, basic dyes, reactive dyes, food grade dyes,etc. Examples of the dyes particularly preferable for the inks in theink jet recording method and can satisfy the performances required suchas color forming characteristic, sharpness, stability, light resistanceand others may include

direct dyes such as C.I. Direct Black 17, 19, 32, 51, 71, 108, 146, 154;

C.I. Direct Blue 6, 22, 25, 71, 86, 90, 106, 199;

C.I. Direct Red 1, 4, 17, 28, 83;

C.I. Direct Yellow 12, 24, 26, 86, 98, 142;

C.I. Direct Orange 34, 39, 44, 46, 60;

C.I. Direct Violet 47, 48;

C.I. Direct Brown 109;

C.I. Direct Green 59, and the like, acid dyes such as

C.I. Acid Black 2, 7, 24, 26, 31, 52, 63, 112,

C.I. Acid Blue 9, 22, 40, 59, 93, 102, 104, 113, 117, 120, 167, 229,234;

C.I. Acid Red 1, 6, 32, 37, 51, 52, 80, 85, 87, 92, 94, 115, 180, 256,317, 315;

C.I. Acid Yellow 11, 17, 23, 25, 29, 42, 61, 71;

C.I. Acid Orange 7, 19;

C.I. Acid Violet 49 and the like, and other dyes such as

C.I. Basic Black 2;

C.I. Basic Blue 1, 3, 5, 7, 9, 24, 25, 26, 28, 29;

C.I. Basic Red 1, 2, 9, 12, 13, 14, 37;

C.I. Basic Violet 7, 14, 27;

C.I. Food Black 1, 2 and the like.

The above examples of dyes are particularly preferred for the inks to beused in the present invention, and the dyes to be used are not limitedto these dyes.

Such a water-soluble dye is used at a proportion generally of about 1 to10 %, by weight more preferably to 5 % by weight in the ink.

The solvent to be used for the ink is a solvent mixture of water with anorganic solvent. As the water, it is preferable to use deionized waterinstead of water in general containing various kinds of ions.

The organic solvent to be used in a mixture with water may preferably beone having a boiling point under normal pressure of 120 ° C or higher,as exemplified preferably by those represented by the formulae shown

    R.sub.1 --O--(C.sub.2 H.sub.4 O).sub.m --R.sub.2           [I]

    HO--(C.sub.2 H.sub.4 O).sub.a (C.sub.3 H.sub.6 O).sub.b (C.sub.2 H.sub.4 O).sub.c H                                                (II) ##STR1##

Typical examples of the compounds represented by the formula [I] areshown in Table 1.

                  TABLE 1                                                         ______________________________________                                        No.     R.sub.1           m      R.sub.2                                      ______________________________________                                        1       CH.sub.3          3      C.sub.2 H.sub.5                              2       C.sub.2 H.sub.5   3      C.sub.2 H.sub.5                              3       C.sub.3 H.sub.7   3      C.sub.3 H.sub.7                              4       C.sub.4 H.sub.9   3      CH.sub.3                                              ##STR2##         3      CH.sub.3                                     6       CH.sub.3          4      CH.sub.3                                     7       C.sub.2 H.sub.5   4      C.sub.2 H.sub.5                              8       C.sub.3 H.sub.7   4      C.sub.3 H.sub.7                              9       C.sub.4 H.sub.9   4      CH.sub.3                                     10      C.sub.2 H.sub.5   5      C.sub.2 H.sub.5                              11      C.sub.3 H.sub.7   5      C.sub.3 H.sub.7                              12      C.sub.5 H.sub.11  5      CH.sub.3                                     13      C.sub.2 H.sub.5   6      C.sub.2 H.sub.5                              14      C.sub.3 H.sub.7   6      C.sub.2 H.sub.5                              15      C.sub.6 H.sub.13  6      CH.sub.3                                     16      C.sub.2 H.sub.5   7      CH.sub.3                                     17      C.sub.3 H.sub.7   7      CH.sub.3                                     18                                                                                     ##STR3##         8      CH.sub.3                                     19      C.sub.3 H.sub.7   8      CH.sub.3                                     20      C.sub.4 H.sub.9   9      CH.sub.3                                     21      C.sub.2 H.sub.5   9      C.sub.2 H.sub.5                              22      C.sub.4 H.sub.9   10     CH.sub.3                                     23      CH.sub.3          12     CH.sub.3                                     24      C.sub.3 H.sub.7   13     CH.sub.3                                     25                                                                                     ##STR4##         15     CH.sub.3                                     26      C.sub.6 H.sub.13  17     CH.sub.3                                     27      C.sub.2 H.sub.5   18     CH.sub.3                                     28      C.sub.2 H.sub.5   19     C.sub.2 H.sub.5                              29      CH.sub.3          20     CH.sub.3                                     ______________________________________                                    

These compounds can be synthesized according to the known methods.

In the formula [I], R₁ and R₂ each independently represent an alkylgroup having 1 to 6 carbon atoms or an aryl group having 8 or lesscarbon atoms, m is a positive integer, preferably 3 to 20.

Particularly when m is within the range of from 3 to 20, the compoundsof the formula [I] have low vapor pressures, and hardly evaporated ataround room temperature to produce no sensible odor.

On the other hand, if m is 2 or lower in the formula [I], thesecompounds have relatively good penetrating force into water andsolubility in a solvent, but they have slightly higher vapor pressuresto produce sensible odor.

Also, these compounds have no effect of preventing clogging at theorifice tip, but contrariwise frequently promote clogging. There isfurther the problem in hygiene of working environment.

On the other hand, when m is 21 or more, the viscosity of the ink willbe markedly increased, whereby there is the problem that fixing speedcannot be improved.

In the formula [I], as the carbon chain of the alkyl group is longer,the effect of penetrating into paper becomes greater. However, if thecarbon atoms in the alkyl group are 7 or more, feathering becomesextremely great similarly as in the case of a surfactant, and it hasbeen further found that its solubility in an aqueous medium will beabruptly lowered with the length of the carbon chain.

Therefore, the alkyl group should preferably have 1 to 6 carbon atoms.

Also, the compound as a whole should preferably have 9 or more carbonatoms. The content of these compounds is limited from the balancebetween the fixing time of ink and feathering but the viscosity of thewhole ink can be controlled by varying the length of m.

The compound of the formula [I], which is a diether, has more mildsurface active ability as compared with monoethers, whereby featheringis hardly caused in the printed matter. Also, as compared withcorresponding polyoxyethylene, it is higher in vapor pressure but lowerin viscosity to be lowered in interface tension with paper, andtherefore it has the effect of increased fixing speed of ink.

Next, the compounds represented by the formula [II] are block copolymersof ethylene oxide (EO) and propylene oxide (PO) of the (EO)_(a) -(PO)btype or (EO)_(a) -(PO)_(b) -(EO)_(c) type, either of which can beobtained according to the methods known in the art.

Of the block copolymers as defined above, those which are useful for theobject of the present invention are those in which a and c, namely thepolymerization degree of EO is 78 or less, and b, namely thepolymerization degree of PO is 2 or more and 15 or less.

The above block copolymers particularly preferred in the presentinvention are exemplified in terms of a, b and c as shown in Table 2.

                  TABLE 2                                                         ______________________________________                                        No.       a         b         c                                               ______________________________________                                        1         3         2         1                                               2         4         3         0                                               3         6         3         0                                               4         5         3         1                                               5         2         4         0                                               6         4         4         4                                               7         6         4         2                                               8         8         4         0                                               9         18        4         2                                               10        4         5         0                                               11        8         5         2                                               12        9         5         1                                               13        8         6         4                                               14        10        6         2                                               15        12        7         2                                               16        3         8         0                                               17        6         8         2                                               18        7         8         1                                               19        10        8         6                                               20        12        8         4                                               21        14        8         2                                               22        39        8         2                                               23        16        9         2                                               24        19        10        1                                               25        20        11        2                                               26        11        12        1                                               27        20        12        4                                               28        22        12        2                                               29        20        14        8                                               30        15        15        15                                              ______________________________________                                    

In the compounds represented by the above formula, if the sum of a and cexceeds 78, in spite of good compatibility with water, the compoundsrepresented by the above formula have too high molecular weights,whereby the viscosity of ink becomes too high and, in spite of littlefeathering during printing, the drying and fixing speed of ink is lowand, as the ink or ink jet recording, discharging characteristic of inkor the shape of ink dot becomes unstable. The same is the case if b istoo small and, while if b is too large there is the fear thatcompatibility with water and drying and fixing speed of ink may becomeinsufficient.

As to the weight ratio of EO in the molecule of the compound representedby the above formula, EO should preferably comprise 20 to 80 % by weightbased on the whole compound to accomplish best the object of the presentinvention.

The compound represented by the formula [III] is obtained by addingethylene oxide to phenol or an alkyl phenol having 1 or 2 alkyl grouphaving 1 to 2 carbon atoms, and the method for producing it per se maybe similar to the method known in the art.

In the prior art, compounds prepared by adding ethylene oxides to alkylphenols have been known as nonionic surfactants. However, such nonionicsurfactants of the prior art have generally 8 to 12 carbon atoms in thealkyl group in order to control appropriately their HLB values. Suchnonionic surfactants have been employed in the ink for ink jet of theprior art and exhibit the action enhancing apparent drying and fixing ofink, namely absorbability of ink into the recording medium. However,when the recording medium is a paper such as low sizing paper, excellentliquid absorbability will contrariwise cause troubles to give rise toexcessive feathering of ink.

The present inventors have studied intensively about such feathering ofthe ink for ink jet, and consequently found that the problem offeathering of ink as mentioned above can be solved and also an inkcapable of giving excellent drying and fixing characteristic of ink evenfor high sizing paper can be obtained by use of an ethylene oxide adductof alkylphenol as described above, in which the alkyl group on thephenol is eliminated or the alkyl group, if any, is made to have 1 or 2carbon atoms, as the moles of ethylene oxide added are made 4 to 20.

Typical examples of preferable compounds of the above formula [III] tobe used in the present invention are as shown below.

                  TABLE 3                                                         ______________________________________                                        Compound No.                                                                            R.sub.3        R.sub.4     n                                        ______________________________________                                        1         Hydrogen atom  Hydrogen atom                                                                             4                                        2         "              "           5                                        3         "              "           6                                        4         "              "           7                                        5         "              "           8                                        6         "              "           10                                       7         "              "           15                                       8         "              "           20                                       9         p-methyl       "           5                                        10        "              "           6                                        11        "              "           7                                        12        "              "           8                                        13        "              "           10                                       14        "              "           15                                       15        p-ethyl        "           6                                        16        "              "           8                                        17        "              "           10                                       18        "              "           12                                       19        p-methyl       o-methyl    6                                        20        "              "           8                                        21        "              "           10                                       22        "              "           12                                       23        p-ethyl        "           10                                       24        "              "           10                                       ______________________________________                                    

As contrasted to the compounds [III] to be used in the present inventionas described above, in the case of medium to high alkyl groups such asnonyl, octyl, dodecyl groups as in the nonionic surfactants of the priorart, the ink which contains such a nonionic surfactant is excellent inabsorbability, but, in the case of a low sizing paper such as plainpapers in general, excessive feathering of ink occurs to impair thequality of printing to a great extent. It has also been proposed to usean example in which the alkyl group is made to have 3 to 4 carbon atomsfrom the balance between drying and fixing characteristic of ink andfeathering. However, even with an alkyl group having such carbon atoms,the problem of feathering for plain papers, etc., cannot be sufficientlysolved, and it is impossible to avoid lowering in quality of printing.

On the other hand, as for the moles of ethylene oxide added (n), if n ismade 3 or less, in spite of excellent effect of increased penetratingforce of ink, vapor pressure becomes higher to give less effect topreventing clogging within the nozzle of the ink jet recording device,and the compatibility with water becomes insufficient, whereby cloggingof the nozzle may be sometimes recognized to be promoted. On thecontrary, if n is 21 or more, the viscosity of ink is increased to makestable from the nozzle hardly achievable, and also the drying and fixingspeed after printing will be very low. The amount of the compoundsrepresented by the above formulae [I]-[III] as described above added inthe ink is not particularly limited, but if the ratio of the compoundrepresented by the above formulae in the ink is less than 0.5 % byweight, the drying and fixing speed of ink becomes insufficient, whileif it exceeds 60 % by weight, the viscosity of the ink may beexcessively increased, and excessive feathering of printed letters mayoccur or stability of the ink may be lowered. Thus, the compoundrepresented by the above formulae should be contained in the inkpreferably at a proportion of 0.5 to 60 wt.%, more preferably 0.5 to 30wt.%.

Further, examples of water-soluble organic solvents which may becontained in combination with

these compounds represented by the formulae [I]·[III] may include alkylalcohols having 1 to 4 carbon atoms such as methyl alcohol, ethylalcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butylalcohol, tert-butyl alcohol, isobutyl alcohol and the like; amides suchas dimethylformamide, dimethylacetamide and the like; ketones orketoalcohols such as acetone, diacetone alcohol and the like; etherssuch as tetrahydrofuran, dioxane and the like; polyalkylene glycols suchas polyethylene glycol, polypropylene glycol and the like; alkyleneglycols having 2 to 6 carbon atoms such as ethylene glycol, propyleneglycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol,thiodiglycol, hexylene glycol, diethylene glycol and the like; glycerin;lower alkyl ethers of polyhydric. alcohols such as ethyleneglycol methyl(or ethyl) ether, diethyleneglycol methyl(or ethyl) ether,triethyleneglycol monomethyl(or ethyl) ether and the like;N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine,sulforane, etc. Of these water-soluble organic solvents. polyhydricalcohols such as diethleneglycol, lower alkyl ethers of polyhydricalcohols such as triethyleneglycol monomethyl(or ethyl) ether arepreferred.

The content of the above water-soluble organic solvent in the ink may begenerally 2 to 70 % by weight of the total weight of the ink, preferably5 to 65 % by weight, and more preferably 10 to 60 % by weight.

The ink of the present invention can also 5 include, in addition to theabove components, surfactants, viscosity controllers, surface tensioncontrollers, etc., if necessary. Particularly, concerning surfactants,since such surfactants as employed in the prior art have great effect onfeathering during printing, and therefore should not be used in a largeamount for the object of the present invention and therefore theiramounts should be limited to, for example, 0.5 % by weight or lower inthe ink, preferably 0.4 % by weight or lower and, more preferably 0.3 %by weight or lower.

The ink to be used in the present invention comprises principally theabove components, and the principal specific feature of the ink to beused in the present invention resides in that, in preparing the inkcomprising the above components, the combination of the water-solubledye used and the organic solvent used is made a specific combination andalso that the mixing ratio of water and the organic solvent is made aspecific ratio. More specifically, while any of the water-soluble dyeand the organic solvent as described above are useful, it is requiredthat a water-soluble dye should be selected so as to have a solubilityof 5 % by weight or less in at least one of the organic solvents beinguses and having preferably a boiling point of 120 ° C or higher and alsoit should be used in a restricted amount as specified above.

The solubility as herein mentioned of a water-soluble dye in an organicsolvent refers to grams of the water-soluble dye dissolved in 100 g ofthe organic solvent under normal pressure at 25 ° C.

With such a specific feature, the ink to be used in the presentinvention is sufficiently in a dissolved state of the dye within therecording instrument or in the nozzle, and the water-soluble dye afterrecording comes out rapidly of the dissolved state with evaporation ofwater to lose its fluidity. As the result, the problems of poor dryingor feathering of ink in various recording medium can be also solved, andrecorded images of high quality and high resolution without featheringcan be formed not only on ink jet recording paper specially prepared asa matter of course but also on plain papers in general.

The recording medium which can be used in the method of the presentinvention may include various paper for ink jet recording proposed inlarge number in the prior art or plastic sheets for OHP to enableexcellent recording as a matter of course, or otherwise copying paper,reporting paper, bond paper, slip papers, continuous business forms,printing paper for computer may be all available, and the paper may beeither low sizing papers or high sizing papers.

When a conventional ink, particularly an ink-jet printing ink is usedfor printing on a plain paper of a low sizing degree with the cellulosefiber exposed on the recording surface, the feathering of the print willbe remarkable, making the high-quality printing impracticable. Incontrast, in the method of the present invention, due to the effect ofthe ink as mentioned above, no feathering of ink occurs even on such aplain paper with low degree of sizing to give printing of high quality.Thus, the method of the present invention is still more suitable whenemploying such a paper with low degree of sizing.

The present invention is particularly useful as the ink jet recordingmethod, and such an ink jet recording method may be of any system,provided that it is a system capable of imparting the ink onto arecording medium which is the object to be ejected against by releasingeffectively the ink from a nozzle. Typical examples of such systems aredescribed in, for example, IEEE Transactions on Industry Application,Vol. JA-13, No.1 (the February and March, 1977 issue) and the Feb. 19,1976 issue, the Jan. 29, 1973 issue and the May 6, 1974 issue of NikkeiElectronics. The systems described in these reports are suitable for thepresent invention and, to explain some of them, there is first theelectrostatic attracting system. This system includes the system inwhich recording is effected by giving a strong electrical field betweena nozzle and an accelerating electrode placed several mm ahead of thenozzle, thereby successively ejecting particulated ink from the nozzleand giving information signals to the deflecting electrodes while theejected inks fly between the deflecting electrodes, and also the systemin which ink particles are ejected in accordance with the informationsignals without deflecting the ink particles, and both are effective forthe present invention.

The second system is the system in which high pressure is applied on theink by a small pump and minute ink particles are ejected forcibly bymechanical vibration of the nozzle by a quartz vibrator, etc., and theink particles ejected are electrically charged corresponding toinformation signals simultaneously with ejection. The charged inkparticles are deflected corresponding to the quantity of the chargeduring passage between the deflecting electrode plates. As anothersystem utilizing this system, there is also the system called microdotink jet system. According to this system, while the ink pressure andexciting conditions is maintained at adequate values within a certainranges, two kinds of large and small ink droplets are generated from thenozzle tip, of which only the droplets with smaller sizes are utilizedfor recording. The specific feature of this system resides in that agroup of minute liquid droplets can be obtained even with a thick nozzleaperture of the prior art.

The third system is the piezoelectric device system and, according tothis system, a piezoelectric device is utilized in place of mechanicalmeans such as pump in other systems as the means for pressurizing ink.This is the system, in which pressure is applied on the ink by themechanical displacements created by giving electrical signals to thepiezoelectric device, thereby ejecting the ink from a nozzle. It is alsopossible to use effectively the ink jet system as disclosed in JapaneseLaid-open Patent Publication No. 59936/1979 in which the ink subjectedto the action of heat energy undergoes abrupt change in volume and theink is ejected from the nozzle through the acting force by such a changein state.

The above examples show preferable recording methods of the presentinvention, and the present invention is not limited to these recordingmethods, but it is of course useful for, for example, ink for use inother printers or writing implements.

The present invention is described in more detail by referring to thefollowing examples, in which parts and % are by weight.

EXAMPLE 1

    ______________________________________                                        Compound No. 2 in Table 1                                                                              7     parts                                          Glycerin                 5     parts                                          Polyethylene glycol 400  5     parts                                          Ethylene glycol          10    parts                                          C.I. Direct Black 154    5     parts                                          Nonionic surfactant      0.1   parts                                          [Emulgen PP-150 (trade mark),                                                 produced by Kao Sekken K.K.]                                                  Water                    68    parts                                          ______________________________________                                         (Solubility of C.I. Direct Black 154 in compound No. 2 in Table 1 being       3.5%)                                                                    

The above respective components were charged in a vessel, stirred for 5hours and the resultant mixture was adjusted to pH 7.5 with 0.1 %aqueous sodium hydroxide.

Next, the mixture was filtered and a pressurization through Fluoroporefilter [trade mark; produced by Sumitomo Denko K.K.] with a pore size of0.45 μm to obtain a recording liquid A of the present invention. Thephysical properties, solubility and odor of the recording liquid Aobtained were evaluated. The results are shown in Table 4.

The above recording liquid A was mounted on an ink jet printer(prototype machine produced by Canon K.K.) which performs recording byutilization of heat energy and printing was effected on continuousbusiness forms and copying paper, and the recording characteristics withrespective fixing characteristic and feathering ware evaluated.

Further, the machine was left to stand for 5 minutes without capping theprinting head, and thereafter printing operation was again performed.

After 3 lines of printing was conducted, the power source of the printerwas turned off and clogging of 24 nozzles was examined. The results areshown in Table 5.

EXAMPLES 2-6

    ______________________________________                                        Recording liquid B                                                                        Compound No. 4 in Table 1                                                                           4    parts                                              Triethylene glycol    5    parts                                  (2)         Diethylene glycol     10   parts                                              C.I. Food Black 2     6    parts                                              Water                 75   parts                                  (Solubility of C.I. Food Black 2 in Compound                                  No. 4 in Table 1 being 1% or less)                                            Recording liquid C                                                                        Compound No. 11 in Table 1                                                                          3    parts                                              N-methyl-2-pyrrolidone                                                                              10   parts                                              Polyethylene glycol   15   parts                                              Hexylene glycol       2    parts                                  (3)         Anionic surfactant    0.1  parts                                              [Caribon B (trade mark),                                                      produced by Sanyo Kasei K.K.]                                                 C.I. Acid Red 8       4    parts                                              Water                 66   parts                                  (Solubility of C.I. Acid Red 8 in Compound                                    No. 11 in Table 1 being 1% or less)                                           Recording liquid D                                                                        Compound No. 17 in Table 1                                                                          20   parts                                              Ethylene glycol       10   parts                                              Nonionic surfactant   0.05 parts                                  (4)         [Nissan nonion K211 (trade mark),                                             produced by Nippon Yushi K.K.]                                                C.I. Direct Blue 86   4    parts                                              Water                 66   parts                                  (solubility of C.I. Direct Blue 86 in compound                                No. 17 in Table 1 being 1.5%)                                                 Recording liquid E                                                                        Compound No. 21 in Table 1                                                                          30   parts                                  (5)         C.I. Direct Blue 199  5    parts                                              Water                 65   parts                                  (Solubility of C.I. Direct Blue 199 in Compound                               No. 22 in Table 1 being 3.5%)                                                 Recording liquid F                                                                        Compound No. 26 in Table 1                                                                          2    parts                                              Compound No. 5 in Table 1                                                                           5    parts                                              Glycerin              10   parts                                  (6)         Ethyleneglycol        10   parts                                              C.I. Direct Yellow 86 2    parts                                              C.I. Acid Yellow 23   2    parts                                              Water                 69   parts                                  (Solubility of C.I. Acid Yellow 23 in Compound                                No. 5 in Table 1 being 1% or less)                                            ______________________________________                                    

Example 1 was repeated except for using the above recording liquids B -F in plate of the recording liquid A in Example 1, and the recordingliquids and recording characteristics were evaluated. The results areshown in Table 4 and Table 5.

                  TABLE 4                                                         ______________________________________                                        Examples:                                                                              Surface                                                              Recording                                                                              tension    Viscosity                                                 liquid   (dyne/cm)  (C.P.)    Solubility*.sup.1                                                                     Odor*.sup.2                             ______________________________________                                        (A)      47.2       2.8       ◯                                                                         ◯                           (B)      50.2       2.0       ◯                                                                         ◯                           (C)      46.1       3.4       ◯                                                                         ◯                           (D)      42.5       2.3       ◯                                                                         ◯                           (E)      53.4       2.5       ◯                                                                         ◯                           (F)      54.7       2.4       ◯                                                                         ◯                           ______________________________________                                         *.sup.1 Evaluation standards                                                  ◯ . . . Ink completely homogenized.                               x . . . Separation of oily substance recognized.                              *.sup.2 Evaluation standards                                                  ◯ . . . Odorless or substantially insensible.                     x . . . Unpleasant feeling felt in office or home.                       

                  TABLE 5                                                         ______________________________________                                                Fixing        Feathering                                              Examples:                                                                             characteristic*.sup.3                                                                       ratio*.sup.4                                            recording                                                                             Fanfold  Copying  Fanfold                                                                              Copying                                                                              Clog-                                 liquid  paper    paper    paper  paper  ging*.sup.5                           ______________________________________                                        (A)     ◯                                                                          ⊚                                                                       ◯                                                                        ◯                                                                        0                                     (B)     ⊚                                                                       ⊚                                                                       ◯                                                                        ◯                                                                        0                                     (C)     ◯                                                                          ⊚                                                                       ◯                                                                        ◯                                                                        1                                     (D)     ⊚                                                                       ⊚                                                                       ◯                                                                        ◯                                                                        1                                     (E)     ⊚                                                                       ⊚                                                                       ◯                                                                        ◯                                                                        0                                     (F)     ⊚                                                                       ⊚                                                                       ◯                                                                        ◯                                                                        0                                     ______________________________________                                         *.sup.3 10 seconds, 30 seconds after printing, the printed portion was        rubbed with a filter paper (trade mark; No. 5C, produced by Toyo Kagaku       Sangyo K.K.).                                                                 ⊚ . . . No smearing after 10 seconds                           ◯ . . . Slight smearing after 10 seconds                          Δ . . . Slight smearing after 30 seconds                                X . . . Considerable smearing after 30 seconds                                *.sup.4 The number of dots with feathering in 300 printed dots was            evaluated in terms of percent.                                                ◯ . . . Less than 10% of feathering                               Δ . . . 10% to less than 20% of feathering                              X . . . 20% or more of feathering                                             *.sup.5 Number of nozzles causing clogging out of 24 nozzles.            

For inks (C) and (D), clogging was cancelled by performing restorationoperation.

EXAMPLES 7-11

The components shown below were stirred for 5 hours, and the resultingmixture was adjusted to pH 7.5 with a 0.1% aqueous sodium hydroxide andfurther filtered under pressurization through a membrane filter with apore size of 0.45 μ (trade name, Fluoropore filter, produced by SumitomoDenko K.K.) to provide the ink of the present invention.

    ______________________________________                                        Recording liquid G                                                                        Compound No. 21 in Table 2                                                                           15  parts                                  (7)         C.I. Direct Black 154  5   parts                                              Water                  80  parts                                  (Solubility of C.I. Direct Black 154 in Compound                              No. 21 in Table 2 being 2%)                                                   Recording liquid H                                                                        Compound No. 6 in Table 2                                                                            20  parts                                              Compound No. 7 in Table 2                                                                            10  parts                                  (8)         Glycerin               5   parts                                              C.I. Food Black 2      4   parts                                              Water                  61  parts                                  (Solubility of C.I. Food Black 2 in Compound                                  No. 6 and 7 in Table 2 being 1% or less, and 1% or                            less, respectively)                                                           Recording liquid I                                                                        Compound No. 27 in Table 2                                                                           8   parts                                              Glycerin               3   parts                                              Tetraethylene glycol   5   parts                                  (9)         Ethylene glycol        15  parts                                              C.I. Acid Blue 254     3   parts                                              Water                  66  parts                                  (Solubility of C.I. Acid Blue 254 in Compound                                 No. 27 in Table 2 being 1.5%)                                                 Recording liquid J                                                                        Compound No. 22 in Table 2                                                                           20  parts                                              Triethylene glycol dimethyl ether                                                                    10  parts                                              Nonionic surfactant (trade name:                                                                     0.1 parts                                              Surfinol 104 produced by Nisshin                                  (10)        Kogyo K.K.)                                                                   Reactive dye (trade name: Kayaseron                                                                  4   parts                                              React Red CN-3B produced by Nippon                                            Kayaku K.K.)                                                                  Water                  66  parts                                  (Solubility of Reaction dye in Compound                                       No. 22 in Table 2 being 3.5%)                                                 Recording liquid K                                                                        Compound No. 20 in Table 2                                                                           6   parts                                              Glycerin               5   parts                                              Polyethyleneglycol 300 10  parts                                  (11)        C.I. Direct Yellow 86  2   parts                                              C.I. Acid Yellow 23    2   parts                                              Water                  75  parts                                  (Solubility of C.I. Direct Yellow 86, C.I. Acid                               Yellow 23 in compound No. 20 in Table 2 being 2%,                             1% or less)                                                                   ______________________________________                                    

Recording was performed in the same manner as Example 1 except for usingthe recording liquids G - J in place of the recording liquid A inExample 1, and the recording characteristics were evaluated. The resultsare shown in Tables 6 and 7.

                  TABLE 6                                                         ______________________________________                                                  Surface                                                                       tension       Viscosity                                             Ink       (dyne/cm)     (C.P.)   Solubility                                   ______________________________________                                        Recording 43.4          3.1      ◯                                liquid G                                                                      Recording 48.3          3.3      ◯                                liquid H                                                                      Recording 45.2          2.9      ◯                                liquid I                                                                      Recording 33.6          3.5      ◯                                liquid J                                                                      Recording 43.4          3.1      ◯                                liquid K                                                                      ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                                     Example                                                          Ink            7        8     9      10  11                                   ______________________________________                                        Discharging stability*.sup.6                                                                 ◯                                                                          ◯                                                                       ◯                                                                        ◯                                                                     ◯                        Fixing characteristic*.sup.3                                                  Continuous slip paper                                                                        ⊚                                                                       ◯                                                                       ⊚                                                                     ◯                                                                     ◯                        Copying paper  ⊚                                                                       ⊚                                                                    ⊚                                                                     ⊚                                                                  ⊚                     Feathering*.sup.4                                                             Continuous slip paper                                                                        ◯                                                                          ◯                                                                       ◯                                                                        ◯                                                                     ◯                        Copying paper  ◯                                                                          ◯                                                                       ◯                                                                        ◯                                                                     ◯                        Clogging*.sup.5                                                                              0        1     0      1   0                                    ______________________________________                                         *.sup.6 Evaluation standards for the dot constitution of a portion of a       printed alphabet letter observed through a magnifying glass.                  ◯ . . . No disturbance observed in dot constitution.              x . . . Disturbance observed or satellite dots occurred in dot                constitution.                                                            

*6 Evaluation standards for the dot constitution of a portion of aprinted alphabet letter observed through a magnifying glass.

o . . . No disturbance observed in dot constitution.

x . . . Disturbance observed or satellite dots occurred in dotconstitution.

EXAMPLES 12-16

The components shown below were stirred for 5 hours, and the resultingmixture was adjusted to pH 7.5 with a 0.1% aqueous sodium hydroxide andfurther filtered under pressurization through a membrane filter with apore size of 0.45 μ (trade name, Fluoropore filter, produced by SumitomoDenko K.K.) to provide the ink of the present invention.

    ______________________________________                                        Recording liquid L                                                                       Compound No. 6 in Table 3                                                                              20  parts                                 (12)       C.I. Direct Black 154    5   parts                                            Water                    75  parts                                 (Solubility of C.I. Direct Black in Compound                                  No. 6 in Table 3 being 4.5%)                                                  Recording liquid M                                                                       Compound No. 3 in Table 3                                                                              20  parts                                            Compound No. 7 in Table 3                                                                              10  parts                                 (13)       Glycerin                 5   parts                                            C.I. Food Black 2        4   parts                                            Water                    61  parts                                 (Solubility of C.I. Food Black in Compound                                    No. 3, No. 7 in Table 3 being 3%, 4.5%, respectively)                         Recording liquid N                                                                       Compound No. 10 in Table 3                                                                             8   parts                                            Glycerin                 3   parts                                            Tetraethylene glycol     5   parts                                 (14)       Ethylene glycol          15  parts                                            C.I. Acid Blue 254       3   parts                                            Water                    66  parts                                 (Solubility of C.I. Acid Red 254 in compound                                  No. 10 in Table 3 being 1%)                                                   Recording liquid O                                                                        Compound No. 21 in Table 3                                                                            20  parts                                            Triethylene glycol dimethyl ether                                                                      10  parts                                            Nonionic surfactant (trade name:                                                                       0.1 parts                                 (15)       Surfinol 104 produced by Nisshin Kagaku                                       Kogyo K.K.)                                                                   C.I. Reactive Red 221    4   parts                                            Water                    66  parts                                 (Solubility of C.I. Reactive Red 221 in compound                              No. 21 in Table 3 being 1%)                                                   Recording liquid P                                                                       Compound No. 2 in Table 3                                                                              6   parts                                            Glycerin                 5   parts                                            Polyethyleneglycol 300   10  parts                                 (16)       C.I. Direct Yellow 86    2   parts                                            C I. Acid Yellow 23      2   parts                                            Water                    75  parts                                 (Solubility of C.I. Direct Yellow 23, C.I.                                    Acid Yellow 23 in Compound No. 2 in Table 3 being 4.5%,                       2%, respectively)                                                             ______________________________________                                    

Recording was performed in the same manner as Example 1 except for usingthe recording liquids L - P in place of the recording liquid A inExample 1, and the recording characteristics were evaluated. The resultsare shown in Tables 8 and 9.

                  TABLE 8                                                         ______________________________________                                                  Surface                                                                       tension       Viscosity                                             Ink       (dyne/cm)     (C.P.)   Solubility                                   ______________________________________                                        Recording 43.6          2.8      ◯                                liquid L                                                                      Recording 41.0          3.5      ◯                                liquid M                                                                      Recording 46.3          2.5      ◯                                liquid N                                                                      Recording 33.6          2.5      ◯                                liquid O                                                                      Recording 52.4          2.3      ◯                                liquid P                                                                      ______________________________________                                    

                  TABLE 9                                                         ______________________________________                                                      Example                                                         Ink             12     13     14  15   16   6                                 ______________________________________                                        Discharging stability*.sup.6                                                                  ◯                                                                        ◯                                                                        ◯                                                                     ◯                                                                      ◯                                                                      X                                 Fixing characteristic*.sup.3                                                  Continous business form                                                                       ⊚                                                                     ◯                                                                        ⊚                                                                  ◯                                                                      ◯                                                                      X                                 Copying paper   ⊚                                                                     ⊚                                                                     ⊚                                                                  ⊚                                                                   ⊚                                                                   Δ                           Feathering*.sup.4                                                             Continuous business form                                                                      ◯                                                                        ◯                                                                        ◯                                                                     ◯                                                                      ◯                                                                      ◯                     Copying paper   ◯                                                                        ◯                                                                        ◯                                                                     ◯                                                                      ◯                                                                      ◯                     Clogging*.sup.5 0      0      0   1    1    10                                ______________________________________                                    

We claim:
 1. A recording method comprising the steps of:jetting liquiddroplets of an aqueous recording liquid onto a recording mediumsubjected to sizing and having fibers exposed on a surface thereof,wherein said aqueous recording liquid comprises 1 to 10% by weight of awater-soluble dye, at least 61% by weight of water, and at least one ofthe compounds represented by formulae (I), (II) or (III) below, wherein,if selected, said compound (I) is contained in said recording liquidwithin a range of 2 to 30% by weight, and said compounds (II) or (III)are contained within a range of 6 to 30% by weight based on the totalweight of the recording liquid:

    R.sub.1 O--(C.sub.2 H.sub.4 O).sub.m --R.sub.2             (I)

    HO--(C.sub.2 H.sub.4 O).sub.a (C.sub.3 H.sub.6 O).sub.b (C.sub.2 H.sub.4 O).sub.c H                                                (II)

    (R.sub.3)(R.sub.4)Ph--O--(C.sub.2 H.sub.4 O).sub.n H       (III)

wherein R₁ and R₂ are independently C₁₋₆ alkyl or C₈ or less aryl, m isfrom 3 to 20, a+c are at most 78, b is from 2 to 15, R₃ and R₄ areindependently hydrogen or a C₁ or 2 alkyl, and n is from 4 to
 20. 2. Arecording method according to claim 1, wherein said recording liquidfurther comprises a polyhydric alcohol or a lower alkyl ether of apolyhydric alcohol.
 3. A recording method according to claim 1, whereinsaid recording liquid comprises a compound represented by the generalformula (I) in an amount of 2 to 30% by weight based on the total weightof the recording liquid.
 4. A recording method according to claim 1,wherein said recording liquid comprises a compound represented by thegeneral formula (II) in an amount of 6 to 30% by weight based on thetotal weight of the recording liquid.
 5. A recording method according toclaim 1, wherein said recording liquid comprises a recording liquidrepresented by the general formula (III) in an amount of 6 to 30% byweight based on the total weight of the recording liquid.
 6. A recordingmethod according to claim 1, wherein said compound of formula (I) isselected from the group consisting of:

    C.sub.2 H.sub.5 O(C.sub.2 H.sub.4 O).sub.3 C.sub.2 H.sub.5

    C.sub.4 H.sub.9 O(C.sub.2 H.sub.4 O).sub.3 CH.sub.3 ##STR5##

    C.sub.3 H.sub.7 O(C.sub.2 H.sub.4 O).sub.5 C.sub.3 H.sub.7

    C.sub.3 H.sub.7 O(C.sub.2 H.sub.4 O).sub.7 C.sub.3 H.sub.7

    C.sub.2 H.sub.5 O(C.sub.2 H.sub.4 O).sub.9 C.sub.2 H.sub.5

    C.sub.2 H.sub.13 O(C.sub.2 H.sub.4 O).sub.17 CH.sub.3.


7. A recording method according to claim 1, wherein said compoundrepresented by formula (II) is selected from the group consisting of:

    HO(C.sub.2 H.sub.4 O).sub.4 (C.sub.3 H.sub.6 O).sub.4 (C.sub.2 H.sub.4 O).sub.4 H

    HO(C.sub.2 H.sub.4 O).sub.6 (C.sub.3 H.sub.6 O).sub.4 (C.sub.2 H.sub.4 O).sub.2 H

    HO(C.sub.2 H.sub.4 O).sub.12 (C.sub.3 H.sub.6 O).sub.8 (C.sub.2 H.sub.4 O).sub.4 H

    HO(C.sub.2 H.sub.4 O).sub.14 (C.sub.3 H.sub.6 O).sub.8 (C.sub.2 H.sub.4 O).sub.2 H

    HO(C.sub.2 H.sub.4 O).sub.39 (C.sub.3 H.sub.6 O).sub.8 (C.sub.2 H.sub.4 O).sub.2 H

    HO(C.sub.2 H.sub.4 O).sub.20 (C.sub.3 H.sub.6 O).sub.12 (C.sub.2 H.sub.4 O).sub.4 H


8. A recording method according to claim 1, wherein said compound offormula (III) is selected from the group consisting of: ##STR6##
 9. Arecording method according to claim 1, including the steps of applyingheat energy to said recording liquid to form a droplet, and applyingsaid droplet to a recording material to carry out recording.